Conventional steam power plant plants have a closed water-steam cycle. In the steam generator so much energy is added to the boiler feed water by combustion of a fossil fuel that it passes into the vaporous aggregate condition. This steam drives a generator via one or several steam turbines and afterwards is liquefied again in one condenser.
As it is not possible to economically store electric energy in big scope, there were already considerations in the past aiming at storing thermal energy in a steam power plant in order to thereby increase the flexibility resp. adaption to net requirements (peak load).
It is known from U.S. Pat. No. 4,003,786 to arrange a chain of heat exchangers parallel to the preheater passage of the steam power plant. Via these heat exchangers it is possible to exchange heat between a part of the condensate stream and a thermo-oil. This means that the heat exchangers are streamed through by condensate on the one hand and a thermo-oil on the other hand. Thus it is possible to confer heat from the condensate to the thermo-oil in times of low demand and to store this heated thermo-oil. When subsequently a high output is requested, it is possible to re-confer the heat stored in the thermo-oil to the condensate via the same heat exchangers and thus to reduce the demand of tapping steam for preheating the condensate. Consequently, the output available at the generator is increased and the demanded peak load can be met in a better way.
This known arrangement is very complex and requires a multitude of heat exchangers as well as two heat reservoirs. For this reason two different heat reservoirs are required, because both heat reservoirs are operated at different temperatures, i.e. approximately 190° and 520° C.
It is the object of the invention to provide a steam power plant which can provide peak load stream and control energy, wherein the apparative effort required therefor is to be preferably low. Furthermore the strengthening of already existing steam power plants is to be possible in a preferably simple manner and with small manipulations of the steam power plant process.